*4.5. Dietary Intervention*

Dietary modifications constitute one of the first choices of treatment for IBS patients [87]. Indeed, a careful history may reveal patterns of symptoms linked to specific food consumption. Although debatable, a high-fiber diet has traditionally been encouraged particularly in IBS-C patients, given the absence of serious side effects and its potential benefit [88,89]. In recent years, there has been a growing clinical and scientific interest in the use of a diet low in FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) in IBS patients. Since its introduction, reports in the literature including several RCTs have reported the efficacy of a low-FODMAP diet in improving global IBS symptoms, visceral pain, bloating, and quality of life [90–96]. However, large and long-term RCTs are still lacking, and various concerns have been raised including diet complexity and cost, risk of nutritional deficiencies, and importantly, an unclear impact on gu<sup>t</sup> microbiome [97–99].

A focus on the role of a gluten-free diet (GFD) in IBS has grown recently, with studies demonstrating the induction of symptoms following gluten consumption in IBS patients [100]. However, evidence to support gluten avoidance in IBS has been conflicting. Moreover, a recent report has suggested that fructans rather than gluten protein are responsible for the symptomatic improvement reported in a gluten-free diet [101]. Further studies are required to evaluate the effect of a GFD on nutritional status, gu<sup>t</sup> microbiota, and long-term outcomes.
